Commonly known magnetic memory devices may include a magnetic tunnel junction pattern (MTJ) that is formed by two magnetic substances and an insulation layer interposed therebetween. The resistance value of the MTJ pattern may be varied according to the magnetization directions of the two magnetic substances with respect to each other. In some embodiments, a switching current Jc0 is passed through the MTJ pattern to vary the magnetization direction of one of the magnetic substances with respect to the other magnetic substance. If the magnetization directions of the two magnetic substances are anti-parallel to each other, the magnetic tunnel junction pattern may have a high resistance value. If the magnetization directions of the two magnetic substances are parallel to each other, the magnetic tunnel junction pattern may have a low resistance value. The difference between the resistance values of the two magnetization states may be used to write/read data.